A vacuum circuit breaker is such sort of circuit breaker where the arc quenching takes place in vacuum. Vacuum Circuit Breaker (VCB) is one where vacuum of the order of 10-6 to 10-10 torr is 3P 100A mccb for industry use. Larger circuit breakers corresponding to these used in electrical power distribution may use vacuum, an inert gasoline similar to sulfur hexafluoride or have contacts immersed in oil to suppress the arc. In contrast to other circuit breakers, they continuously monitor all secondary circuits. After the ultimate arc interruption, there is rapidly increase of dielectric energy which is peculiar of the vacuum breaker. As the present within the solenoid increases beyond the rating of the circuit breaker, the solenoid’s pull releases the latch which then permits the contacts to open by spring motion. This excessive dielectric energy makes it potential to quench a vacuum arc inside very small contact gap. Our circuit breakers are utilized in panelboards, switchboards, motor management centers, control panels, combination starters, individual enclosures, and bus duct plug-in models. The vacuum circuit breaker consists of fixed contact, shifting contact and arc defend mounted inside the vacuum chamber. Typical home panel circuit breakers are rated to interrupt 10 kA (10000 A) short-circuit current. When an arc is opened by transferring aside the contacts in a vacuum, an interruption occurs at the first current zero. A direct present circuit breaker will have blow-out coils which generate a magnetic area that quickly stretches the arc when interrupting direct present. When the contacts of the breaker are opened in vacuum (10^-7 to 10^-5 torr), an arc is produced between the contacts by the ionisation of steel vapours of contacts. The introduction of the chrome copper contacts brought a reduction of the chopping current to between 2 to risk of impermissible over voltages arising resulting from present chopping has been reduced to a negligible degree. Table 1. Traits of the SF6 and vacuum current interrupting applied sciences. Vacuum circuit breaker memiliki ruang hampa udara untuk memadamkan busur api, pada saat circuit breaker terbuka (open), sehingga dapat mengisolir hubungan setelah bunga api terjadi, akibat gangguan atau sengaja dilepas. The variety of faulty tripping occurred in whole life span of circuit breaker generally relies upon upon the situation of the system, high quality of surroundings situation and system. Under brief-circuit conditions, the calculated or measured maximum prospective brief-circuit present could also be many instances the conventional, rated present of the circuit. This is due to the truth that at excessive voltages (above 38 kV) greater than two numbers of the circuit breaker are required to be related in collection. As the current in the solenoid will increase past the score of the circuit breaker, the solenoid’s pull releases the latch, which lets the contacts open by spring motion. In the meanwhile it is accepted that an oxygen free copper chromium alloy is the very best materials for High voltage circuit breaker. Miniature and molded case circuit breakers are normally discarded when the contacts are worn, but power circuit breakers and excessive-voltage circuit breakers have replaceable contacts. The traits of MV breakers are given by international requirements reminiscent of IEC 62271 Medium-voltage circuit breakers nearly always use separate present sensors andprotective relays, as an alternative of counting on constructed-in thermal or magnetic overcurrent sensors. High-voltage AC circuit breakers are routinely out there with scores as much as 765,000 volts. Low voltage circuit breakers are basically the safety in opposition to overloading, quick circuits and earth leakage whereas medium voltage circuit breakers present centralized management and safety for medium voltage power tools and circuitry in business and industrial installations together with transmission and distribution strains. These new forms of breakers are cumbersome and cumbersome. In this method, the vacuum circuit breaker prevents the restoration of the arc by producing a excessive dielectric strength in the contact area after the present zero.